Explict Value can't be inserted in Table when IDENTITY_INSERT is OFF - entity-framework

Question

I get an error when I try to insert a value in my Table.
_dltype is an object of type BRIDownloadType.
using (var db = new BRIDatabase())
{
foreach (var client in db.BRIClients)
{
var todo = new BRIToDo
{
BRIClient = client,
BRIDownloadType = _dltype,
};
db.BRIToDos.Add(todo);
}
db.SaveChanges();
}
Now I get the error:
An Explict Value can't be inserted in the Idendity Column in the BRIDownloadTypes-Table when IDENTITY_INSERT is OFF.
My 2 Tables are
BRIDownloadType
public class BRIDownloadType
{
[Key]
public int DlTypeId { get; set; }
[Required]
[StringLength(15)]
public string DlType { get; set; }
public string Username { get; set; }
public string Password { get; set; }
public virtual ICollection<BRIToDo> BRIToDo { get; set; }
}
BRITodo
public class BRIToDo
{
[Key]
public int ToDoId { get; set; }
[ForeignKey("BRIClient")]
public int ClientId { get; set; }
[ForeignKey("BRITask")]
public int TaskId { get; set; }
public virtual BRIClient BRIClient { get; set; }
public virtual BRITask BRITask { get; set; }
[ForeignKey("BRIDownloadType")]
public int DlTypeId { get; set; }
public virtual BRIDownloadType BRIDownloadType { get; set; }**
}
The interesting thing is, if I do something with my _dltype object, I can use it.
The following code is working and I don't understand why, I'm inserting the exact same object.
using (var db = new BRIDatabase())
{
var dl = db.BRIDownloadTypes.FirstOrDefault(c => c.DlTypeId == _dltype.DlTypeId);
foreach (var client in db.BRIClients)
{
var todo = new BRIToDo
{
BRIClient = client,
BRIDownloadType = _dltype,
};
db.BRIToDos.Add(todo);
}
db.SaveChanges();
}
Can anybody explain to me, why the last approach is working and the first is throwing that error? I just added the line
var dl = db.BRIDownloadTypes.FirstOrDefault(c => c.DlTypeId == _dltype.DlTypeId)
But I'm still inserting the same object. If I insert the Id of the object instead of the object it is also working fine. I have no idea whats going on there.